Rewrite .NET Framework codebases to Go with LEAP Protocol

If you’re asking “how do I rewrite .NET Framework to Go,” we do it by extracting executable specifications from your existing C# app, generating tests from those specs, implementing the Go system in parallel, and rolling it out with parity. Concretely: we use the LEAP Protocol (spec-first, test-gated, agent-agnostic). First, we mine specs from your ASP.NET MVC/Web API or WCF endpoints, data contracts, config, and persistence layer (Entity Framework or ADO.NET), plus observable behaviors and edge cases. Then we generate a comprehensive test suite: HTTP contract tests, database golden tests, property-based checks for business rules, and migration harnesses that run against both the .NET legacy and the new Go implementation. Next, we implement the Go services in parallel—typically with Gin/Chi/Fiber for HTTP, sqlc/GORM/ent for data, and asynq/cron for jobs—keeping identical inputs/outputs and side-effects. Finally, we roll out with parity using side-by-side routing, canaries, and telemetry so production behavior matches before full cutover. The result is a predictable migration from Windows-bound .NET Framework to portable, container-friendly Go with zero-surprise functionality and measurable equivalence.

Why Go for .NET Framework migrations

Static binaries and fast cold starts simplify containerization and scaling versus .NET Framework’s Windows-only runtime and IIS hosting.
Concurrency via goroutines/channels maps well from Task-based code while reducing thread scheduling overhead typical in TPL.
Cross-platform by default: Linux-first deployment, easy CI/CD, and slimmer base images than Windows Server/IIS.
Minimal runtime and memory footprint helps with dense Kubernetes scheduling and predictable tail latencies.
Strong standard library (net/http, context, encoding/json/xml) and first-class OpenTelemetry support fit modern service observability.

Our methodology

Spec extraction from C#: - Parse controllers, WCF contracts, filters, and model binders via Roslyn/IL inspection; capture OpenAPI/Swagger if present. - Diff EF LINQ queries against actual SQL; snapshot schema/migrations; record config (web.config/app.config) and side-effects (MSMQ, file I/O, email, caches).
Test generation and parity harness: - Create black-box HTTP tests, golden database fixtures, and property-based tests for business rules. - Build a runner that executes the same tests against the .NET app and the Go service to ensure behavior parity.
Parallel Go implementation: - HTTP: Gin/Chi/Fiber with strict request/response models; middleware for auth, localization, and error mapping. - Data: sqlc/GORM/ent; explicit transactions (sql.Tx) mirroring TransactionScope semantics; idempotent migrations. - Jobs/queues: asynq or Temporal; migrate MSMQ/WCF queues to NATS/Kafka/RabbitMQ bridges when needed.
Interop and incremental rollout: - Route-by-route shadowing via NGINX/Envoy or IIS ARR; WCF to gRPC/REST adapters; dual-write toggles for data transitions. - Built-in tracing/metrics (OpenTelemetry) to validate SLOs against legacy.
Hardening and cutover: - Load/perf tuning, GC and memory profiles, security review, and failure drills; then canary, ramp, and decommission.

Specific .NET Framework concerns we handle

WCF to gRPC/HTTP: Mapping DataContract/ServiceContract, FaultException to structured errors; translating message contracts and operation behaviors.
ASP.NET MVC/Web API model binding: Type-converting form/query handlers (decimal, DateTime, culture-specific formats) to explicit Go DTOs and validators.
Entity Framework/LINQ: Translating lazy-loading and IQueryable to explicit SQL (sqlc) or careful ORM usage; preserving transaction scopes and isolation levels.
Windows-only dependencies: MSMQ, Registry, COM interop, System.Drawing/GDI+; provide Linux-friendly replacements, wrappers, or service splits.
Auth and identity: Forms/Windows auth, System.IdentityModel, OWIN to OAuth2/OIDC (go-oidc), JWTs, and cookie/session strategies with CSRF/anti-forgery parity.
Error handling semantics: Exception filters to Go error values; consistent HTTP status mapping and correlation IDs via context.

Proof

sqlite-leap — five SQLite engines generated from one spec: https://github.com/safitudo/sqlite-leap
semver-leap — 5,632 passing tests from a single semantic-versioning spec: https://github.com/safitudo/semver-leap
LEAP Protocol reference implementation and runner: https://github.com/safitudo/leap

These public artifacts demonstrate spec-first, test-gated, agent-agnostic delivery: one spec, multiple faithful implementations with exhaustive tests.

Pricing & timeline

Typical engagement: 4–12 weeks depending on service count, data complexity, and interop needs.
We deliver a fixed-price proposal after a 3–5 day discovery (repo access, architecture brief, target SLOs).
Typical ranges: $40k–$120k for small-to-medium services; large monolith splits quoted after spec sampling.
Deliverables: parity test suite, Go services/modules, migration/rollback plan, performance report, and operator runbooks.

Ready to migrate off .NET Framework with zero-surprise parity and modern ops? Email hello@leapagentic.com with your repo link and a short description of the target scope. We’ll run a quick spec sample and return a fixed proposal.

Leap Agentic is distinct from Legacyleap.ai and Impetus Leap AI.